The invention relates to a method in which a sequence of notes for data sets is stored in a write mode in a memory unit for a data value of a datum. At least a part of the sequence of notes is read and processed in a read mode in order to identify certain data sets.
The sequence of notes is referred to as a search list in one known computer-aided search method. The datum is, for example, the surname of a person. The value of the datum is, for example, the surname “Meier”. The sequence of notes for the data value “Meier” then contains notes of data sets for persons having the surname “Meier”. The individual data sets usually also contain other data fields, for example the first name and a telephone number in addition to the surname. Inverted search lists or inverted sequences of notes that are stored for another datum, for example for certain first names, are used in order to simplify the search for the data in the other data fields.
It is known to store the number of a dataset as a note. A data set can be identified by the number with the aid of a database system because the number of the data set concerned is also stored in a data field of each data set. Other known methods calculate from the number noted in the sequence of notes a memory address at which the relevant data set is stored. The number itself does not have to be stored in a data field of the data set in this case. Methods are also known, however, in which the notes are memory addresses at which the data sets are to be found. The known methods have the disadvantage that a large memory area is required to store the sequence of notes. If, for example, there are several thousand data sets, more than 16 bits are required in each case to note the numbers. Usually 32 bits are chosen, as this option corresponds to the data word width of known processors. Depending on the size of the memory, it is often necessary to use several data words of 32 bits each to store memory addresses.
The linking of two sequences of notes with the aid of logic operations is complex, as only two numbers or two addresses can be linked with each other with each logic operation. This makes the linking of very long lists in particular most demanding of processor time.
Additional advantages, aspects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The aspects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.